Oral malodorous compound causes apoptosis and genomic DNA damage in human gingival fibroblasts.
OBJECTIVE
Volatile sulfur compounds are the main cause of halitosis. Hydrogen sulfide is one of these volatile sulfur compounds and the principal malodorous compound in physiological halitosis. Periodontally pathogenic activities of hydrogen sulfide have been previously reported. Hydrogen sulfide induces apoptotic cell death in aorta smooth muscle cells and in other tissues. Apoptosis plays an important role in the onset and progress of periodontitis. The objective of this study was to determine whether hydrogen sulfide causes apoptosis in human gingival fibroblasts.


METHODS
Necrotic cells were detected using a lactate dehydrogenase assay. Apoptosis was ascertained using a histone-complexed DNA fragment assay and flow cytometry. The level of caspase 3, a key enzyme in apoptotic signaling, was also measured, and the effects of hydrogen sulfide on reactive oxygen species and superoxide dismutase were assessed. DNA damage caused by hydrogen sulfide was examined by means of single-cell gel electrophoresis.


RESULTS
After 72 h of incubation with 100 ng/mL of hydrogen sulfide, necrosis was found in less than 10% of human gingival fibroblasts, whereas apoptosis was significantly increased (p < 0.05). Superoxide dismutase activity was strongly inhibited, and reactive oxygen species production was enhanced, after 48 and 72 h of incubation. Caspase 3 activity was also increased after 72 h of incubation (p < 0.01). Tail length, percentage of DNA in tail, and tail moment, measured by single-cell gel electrophoresis, were also intensified after 72 h of incubation (p < 0.001).


CONCLUSIONS
Hydrogen sulfide caused apoptosis and DNA damage in human gingival fibroblasts. An increased level of reactive oxygen species stimulated by hydrogen sulfide may induce apoptosis and DNA strand breaks.
Yaegaki
K
K
Department of Oral Health, School of Life Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan. yaegaki-k@tky.ndu.ac.jp
Qian
W
W
Murata
T
T
Imai
T
T
Sato
T
T
Tanaka
T
T
Kamoda
T
T
D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D053938:DNA Fragmentation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects* / Q000473:pathology; D005434:Flow Cytometry; D016166:Free Radical Scavengers / Q000032:analysis; D015894:Genome, Human / Q000187:drug effects; D005881:Gingiva / Q000187:drug effects / Q000473:pathology*; D006209:Halitosis / Q000378:metabolism*; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology* / Q000633:toxicity; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D009336:Necrosis; D011419:Propidium; D017382:Reactive Oxygen Species / Q000032:analysis; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000187:drug effects; D013997:Time Factors; D014343:Trypan Blue
D017304:Annexin A5; D004396:Coloring Agents; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D011419:Propidium; D004247:DNA; D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase; D053148:Caspase 3; D014343:Trypan Blue; D006862:Hydrogen Sulfide